Angle plates are usually connected and fastened by well-known means such as welding, screws, bolts and nuts, or by pressure and the like. All these methods, however, have disadvantages which hamper their use.
Welding, for example, apart from producing a connection which is difficult repair and maintain, has as its greatest drawback the fact that welded structures are usually heavy and bulky and, therefore, are difficult to transport from their place of manufacture to the site where they will be installed. The use of screws usually results in unstable and weak structures which tend to become crooked and unstable. Bolts and nuts are, in some cases, difficult to fasten because often one of them cannot be easily reached with a fastening tool. Finally, pressure-fit connecting elements are usually made from a rigid plastic material which breaks easily when subjected to heavy weights.